OBJECTIVE: To determine the loss in brain substance and the alteration in brain function 12 years after brain damage incurred during the Vietnam War. The resource for this is a Registry of 1500 Head Injuries compiled in the field by military surgeons from 1967 to 1970, and a subsequent Records Review carried out between 1975 and 1979. To achieve this objective a plan is being developed to complete this study by an in-hospital examination of 1000 of these subjects and 200 controls. The latter will utilize an unique approach to the loss or alteration in structure, i.e., computerized axial tomography, and other techniques, not available in previous studies of functional sequelae.